扎鲁特旗三叠纪侵入岩地球化学特征及其意义

Geochemical characteristics of Triassic intrusive rocks in Zalute Banner and their significance

研究区内金属矿床多赋存于三叠纪侵入岩与地层接触带中,因此对于侵入岩侵位机制的研究显得尤为重要,本文通过对区内二长花岗岩样品进行测试分析得出以下结论:区内二长花岗岩SiO2含量为76.72%,Al2O3含量为12.0%,K2O+Na2O(ALK)为7.17%,A/CNK=1.21,σ=1.52,显示出岩石属钙碱性系列;样品∑REE一般为(102.42~122.11)×10-6,个别为72.55×10-6,含量较低,(La/Yb)N=7.42~15.89,(La/Sm)N=5.45~5.84,具有轻稀土富集及分馏程度中等特征;岩体形成于非造山的花岗岩板内。

Metal deposits occur mostly in the contact zone between Triassic intrusive rocks and strata in the study area,so it is particularly important to study the emplacement mechanism of intrusive rocks.Through testing and analyzing the samples of monzonitic granite in the study area,the following conclusions are drawn:(1) SiO2 content of monzonitic granite is 76.72%,Al2O3 content is12.0%,K2O+Na2O (ALK) is 7.17%.A/CNK=1.21,σ=1.52,indicating that the rocks belong to calc-alkaline series.The REE of samples range from102.42 to122.11 ×10 -6,and the contents of individual samples range from 72.55×10 -6,(La/Yb) N=7.42-15.89,(La/Sm) N=5.45-5.84,which is characterized by medium enrichment and fractionation of light rare earth elements.Rock bodies are formed in non-orogenic granite slabs.